1. Field of the Invention
The subject invention relates to methods and apparatus for mounting a device and adjusting its position, to isthmian precision mounts, to apparatus and methods for mounting magnetic heads, especially for video signal recording and playback equipment or magnetic tape recording and playback apparatus, and to rotary magnetic head assemblies.
2. Description of Prior Art
A large variety of methods and apparatus for mounting a device and adjusting its position have become known over the years. The quest for such methods and apparatus has become intensified with the advent of magnetic tape recording and other techniques wherein the precise adjustment of a recording and/or playback head can be extremely important for an accurate and faithful recording and reproduction of information.
By way of example, reference may be had to the following patents dealing with magnetic head positional adjustments and being herewith incorporated by reference herein: U.S. Pat. No. 2,678,971, by E. Barany, issued May 18, 1954, U.S. Pat. No. 2,897,288, by J. Wijchman, issued July 28, 1959, U.S. Pat. No. 3,455,559, by R. C. Wilson, issued July 15, 1969, U.S. Pat. No. 3,539,191, by Kozo Yamamoto, issued Nov. 10, 1970, and U.S. Pat. No. 3,679,841, by Herger et al., issued July 25, 1972.
The head adjustment precision attainable by these prior-art devices was necessarily limited by their nature.
Higher precision for such high-quality applications as instrumentation tape recording is attainable with the azimuth adjustment and magnetic head mounting technique and structure disclosed in U.S. Pat. No. 3,794,769, by J. J. Neff, issued Feb. 26, 1974, and herewith incorporated by reference herein. Briefly, the azimuth adjustment for magnetic recording heads and other devices according to that patent has a rotatable member with an inclined surface relative to an axis of rotation. A mount for the recording head or other device has a pair of spaced cam followers which are yieldably applied to the inclined surface of the rotatable member. The mount further has a resilient portion which is typically of a reduced or restricted design. To effect azimuth adjustments, the rotatable member is rotated whereby the mount is selectively twisted.
While the latter prior-art device has been and still is very successful in practice, it, too, has its limitations. For instance, that prior-art device has not so far been applied to rotating magnetic recording heads.
In this respect, reference may be had to U.S. Pat. No. 2,773,120, by E. E. Masterson, issued Dec. 4, 1956 and showing an early version of the now widely used rotating magnetic head disk and associated drum structure about which magnetic recording tape is wrapped in order to record magnetic video information and other high frequency signals in a slant track pattern. Another well-known video recording technique in which rotating magnetic heads are used is the transverse-scan method in which the heads rotate in a plane extending perpendicularly to the advancing magnetic recording tape.
In the practice of these techniques, precise elevational and azimuth adjustment of the rotatable heads can become very important to the accuracy and fidelity of the recorded information, as well as to its faithful reproduction.
In connection with the more general scope of the subject invention, reference may, for instance, be had to U.S. Pat. No. 1,676,114, by W. J. Rusdell, issued July 3, 1928, and U.S. Pat. No. 2,294,437, by C. E. Allen et al., issued Sept. 1, 1942, and showing tilting head devices. In practice, those structures would be far too complex for the purposes herein contemplated and, in the case of rotating recording and playback devices, too bulky and of insufficient inherent accuracy.